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I Hilgert

Publications and source records attributed to I Hilgert.

At least 37 records · Page 2Linked to original sources
PubMed1995

An alternative way of CD4 and CD8 association with protein kinases of the Src family.

The T-lymphocyte co-receptors of MHC glycoproteins CD4 and CD8 are known to be associated with the protein tyrosine kinase Lck via cysteine-containing sequences in the cytoplasmic domains of CD4 and CD8 and in the N-terminal domain of Lck. Here we demonstrate that a fraction of CD4 and CD8 molecules are associated with very large, detergent-resistant complexes containing several glycosylphosphatidylinositol-anchored proteins, (glyco)lipids, and protein tyrosine kinases Lck and Fyn but apparently no other major transmembrane proteins. Association of Lck and Fyn with these large complexes is, in contrast to simple CD4/CD8-Lck complexes, not sensitive to alkylation with iodoacetamide. These large complexes therefore represent an alternative way of association of CD4 and CD8 with the protein tyrosine kinases, which may play a role in signaling through these receptors.

CD4 Antigens↗
PubMed1994

Association of four antigens of the tetraspans family (CD37, CD53, TAPA-1, and R2/C33) with MHC class II glycoproteins.

Four of the tetraspans family antigens expressed in B cells, CD37, CD53, TAPA-1, and R2/C33, as well as at least two other molecules, CD19 and CD21, coprecipitate with DR antigens from mild detergent lysates of human B-cell lines and tonsillar B cells. Coprecipitation and preclearing experiments indicate the existence of large multicomponent complexes containing jointly the seven components, although some "incomplete" complexes lacking some of the components may also exist. The complexes contain only a relatively small fraction of the total cellular pool of relevant molecules. The existence of these "tetraspans-DR complexes" may be related to the previously reported antiproliferative and signaling effects of antibodies against most of their components.

Antibodies, Monoclonal↗
PubMed1994

Association of GPI-anchored glycoproteins with other components of the leucocyte membrane.

The leucocyte surface glycosylphosphatidylinositol (GPI)-anchored membrane proteins are localized within specific membrane microdomains which also contain specific (glyco)lipids and intracellular proteins including protein kinases. These "GPI-domains" are devoid of most abundant transmembrane proteins, but in T-cells they appear to contain small amounts of CD4 and CD8 and in B-cell lines, small amounts of CD10. The existence of these relatively detergent-resistant membrane microdomains explains the signal-transducing ability of GPI-anchored receptors. In addition to the "GPI-microdomains", several other types of analogous very large detergent-resistant complexes/domains appear to exist, such as those containing T-cell receptor, others containing CD45R molecules associated with a protein kinase, and still others composed mainly of several proteins of the tetraspan family. Therefore, we suggest that the leucocyte surface is a mosaic of microdomains of unique composition associated with specific signal-transducing molecules.

Antigens, CD↗
PubMed1994

Augmentation of NK cell activity and proliferation in cultured lymphocytes of leukemic patients by monoclonal antibodies CD3 and interleukin-2.

The aim of the present study was to induce NK cell activity in peripheral mononuclear cells (PMNC) of normal individuals or of leukemic patients. For this purpose, monoclonal antibodies (mAbs) anti-CD3 (MEM 57, OKT 3 and MEM 92), anti-CD59 (MEM 43) and anti-CD43 (MEM 59) were tested. MEM 43, MEM 59, MEM 57 and OKT 3 stimulated markedly the NK activity in fresh isolated PMNC of normal individuals, whereas the cytotoxicity in 3-day cultivated PMNC was enhanced only by MEM 57 and OKT 3. In comparison to interleukin-2 (IL-2), MEM 57 and OKT 3 induced less PMNC cytotoxicity but more cell proliferation. MEM 92 (anti-CD3, IgM) compared to MEM 57 or OKT 3 (anti-CD3, IgG) did not show any effect on both reactions mentioned above. PMNC of untreated leukemic patients exerted very negligible NK cell activity. Following 3-day culture of leukemic PMNC with OKT 3 or IL-2 the anti-K 562 cytotoxicity was markedly enhanced. In some cases the stimulating effect was more pronounced by IL-2, in others by OKT 3. Nevertheless, the best effect was gained in 7 out of 12 patients using a combination of IL-2 and OKT 3. On the other hand, OKT 3 did not synergize with IL-2 in normal PMNC culture.

Antibodies, Monoclonal↗
PubMed1993

[Ratios of surface markers (CD) on peripheral blood lymphocytes in the working-age Czech population].

The authors present an account of lymphocytic CD signs in adult men (mean age 34 years) and women (mean age 29 years) of the Czech population. Mean values and standard deviations (s.d.) are given for men/women: CD2: 79.6% (6.6)/86.4% (5.3), CD 3: 71.5% (7.4)/81.1% (7.4), CD4: 42.4% (6.3)/48.4% (8.5), %CD45RA+ v CD4+: 41.7% (14.1)/47.3% (13.9), CD5: 69.5% (7.0)/76.00% (6.5), CD8: 33.9% (9.3)/29.8% (6.8). CD10: 1.9% (1.3)/2.5% (1.6), CD11c: 8.3% (4.7)/10.9% (4.4), CD16: 8.3% (3.8)/4.4% (2.3), CD19: 11.5% (4.0)/8.8% (3.2), CD20: 14.7% (4.7)/11.3%, CD22: 10.6% (9.2)/8.9% (3.5), CD45RA: 56.7% (7.6)/61.7% (7.8), CD56: 15.1% (5.7)/16.0% (6.5), CD57: 13.7% (7.9)/8.5% (6.3), CD71: 1.9% (1.3)/3.5% (1.7) a HLA DR: 22.1% (6.4)/19.6% (7.1), DP: 16.3% (7.1)/13.5% (4.9), DQ: 10.9% (5.8)/7.2% (3.2), BJK: 2.6% (2.2)/2.1% (1.1), BJL: 1.8% (1.2)/2.1% (1.3), ratio CD4/CD8 1.35 (0.49)/1.75 (0.69). The examination were made on an apparatus FACScan (Becton Dickinson).

Adult↗
PubMed1993

Monoclonal antibodies suitable for plum pox virus determination.

Monoclonal antibodies (MAbs) to plum pox virus (PPV) were obtained after immunization of BALB/c mice with purified PPV-W isolate. Spleen cells from a mouse showing a high serum titer were used for fusion with Sp2/0-Ag14 myeloma cells. Culture supernatants were screened for specific antibody production against PPV-W isolate using indirect ELISA. A total of six stable hybridoma lines producing MAbs of IgG class were obtained. All four PPV isolates tested (W, A, D and M) can be distinguished by these MAbs. Two highly efficient antibodies were chosen for practical purposes, and their applicability in PPV diagnostics has been studied since 1989 in parallel with polyclonal antibodies and commercial kits (Boehringer, Bioreba). The experiments have proven comparable sensitivity with a detection limit ranging between 10 and 50 ng of virus per ml sample. In routine diagnostics of plums, peaches and apricots our MAbs ranked at least as high as the commercial kits.

Animals↗
PubMed1991

The human leucocyte antigen CD48 (MEM-102) is closely related to the activation marker Blast-1.

The glycosyl phosphatidylinositol (GPI)-linked antigen recognized by monoclonal antibody (mAb) MEM-102 is expressed on all peripheral blood lymphocytes, both resting and activated. Its properties are very similar to a previously described activation antigen, Blast-1. The amino acid sequence deduced from the structure of cloned cDNA is identical to that of the Blast-1 antigen except for a single amino acid residue. There are several other minor differences in the nucleotide sequence of the Blast-1 and MEM-102 cDNAs that do not affect the predicted structure of the polypeptide product. The amino acid sequence of the first 15 N-terminal residues of the antigen purified from Raji cells is found in the deduced sequence close to the presumed boundary between the leader peptide and mature polypeptide. Properties of the recombinant product expressed in COS cells are similar to the antigen isolated from peripheral blood mononuclear cells (PBMNCs) or B-and T-cells lines. The antigen purified on immobilized mAb MEM-102 is recognized by all six known CD48 mAbs under western blotting conditions. COS cells transfected with MEM-102 cDNA react with all the CD48 mAbs. It is concluded that mAb MEM-102 is directed against the as yet poorly characterized antigen CD48, which is therefore structurally closely related to Blast-1. Several possibilities are discussed that might account for the apparent discrepancy between the broad pan-leucocyte expression of the between the broad pan-leucocyte expression of the MEM-102/CD48 antigen and much more restricted expression of the epitope recognized by the previously described mAb defining the Blast-1 antigen.

Amino Acid Sequence↗
PubMed1991

A monoclonal antibody applicable for determination of C-peptide of human proinsulin by RIA.

BALB/c, (BALB/c x B10.A)F1 and (BALB/c x B10)F1 hybrid mice were immunized with C-peptide of human proinsulin. The (BALB/c x B10.A)F1 hybrids were the best responders and yielded 3 hybridomas secreting specific monoclonal antibodies. One of them, C-PEP-01, bound the C-peptide with high affinity (Kas = 1.1 x 10(9) l/mol), cross-reacted fully with human proinsulin but not with insulin, glucagon or somatostatin and apparently recognized the regions of C-peptide comprising amino acid residues 8-13 and 25-31. A RIA system could be set up employing this monoclonal antibody suitable for estimation of C-peptide concentrations in a diagnostically useful range (1-50 ng/ml).

Amino Acid Sequence↗
PubMed1990

Monoclonal antibodies against human leucocyte antigens. IV. Antibodies against subunits of the LFA-1 (CD11a/CD18) leucocyte-adhesion glycoprotein.

Six monoclonal antibodies were prepared that recognize a broadly expressed antigen composed of noncovalently associated 95 kDa and 180 kDa subunits. Antibodies MEM-25, MEM-83 and MEM-95 are shown to react with a determinant(s) present on the isolated larger subunit identified as the CD11a glycoprotein, MEM-48 reacts with the isolated smaller subunit which is identical to the CD18 glycoprotein. Antibodies MEM-30 and MEM-94 recognize probably a determinant in the CD11a/CD18 complex (i.e., LFA-1 antigen) dependent on association of the constituent chains. Cytotoxic activity of NK cells in inhibited by antibodies MEM-25, MEM-95 and less strongly by MEM-30 and MEM-94.

Animals↗
PubMed1989

Structural relationship between the soluble and membrane-bound forms of human monocyte surface glycoprotein CD14.

The carboxy-terminal amino acid sequence of the soluble form of the 53,000 mol. wt monocyte surface antigen, CD14, was determined by carboxypeptidase Y digestion and compared with the complete amino acid sequence of this protein as predicted from the structure of cloned cDNA [Goyert et al. Science 239, 497-500 (1988)]. The soluble antigen isolated from urine appears to lack eight C-terminal amino acid residues predicted for the full-size translation product, but possesses a major part of the C-terminal hydrophobic domain originally suggested as the membrane-spanning segment. The CD14 antigen can be removed from the monocyte surface by phosphatidylinositol-specific phospholipase C treatment, indicating that this glycoprotein is anchored in the membrane by a phospholipid and is not a transmembrane protein. The soluble form occurring in serum and in supernatants of cultured monocytes thus probably arises by phospholipase-mediated cleaving off the cell surface antigen. A sensitive sandwich ELISA was developed using a monoclonal anti-CD14 antibody, MEM-18, and polyclonal rabbit anti-CD14 antiserum for quantitation of the soluble antigen concns in sera and cell culture supernatants. Using this assay, the antigen present in the supernatant of phospholipase treated peripheral blood mononuclear cells could be estimated. The assay was also used for estimation of the concns of the soluble form of the CD14 antigen in human sera.

Amino Acid Sequence↗
PubMed1989

Characterization of a broadly expressed human leucocyte surface antigen MEM-43 anchored in membrane through phosphatidylinositol.

A monoclonal antibody MEM-43 was prepared, which recognizes an antigen expressed on all peripheral blood leucocytes, on erythrocytes and several cell lines, but is absent from U937, Nalm-6, Daudi and Raji cell lines. The antigen isolated by immunoaffinity chromatography from several cell lines is an 18,000-25,000 mol. wt glycoprotein. An apparently identical antigen isolated from erythrocytes binds to several lectins and has a 14,000 mol. wt polypeptide backbone, modified by an endoglycosidase F-sensitive carbohydrate moiety. The epitope recognized is reduction-sensitive. The sequence of N-terminal 17 amino acid residues was determined; five out of six N-terminal amino acids are identical to those found at the N-terminus of the mouse lymphocyte surface antigen Ly-6C. The antigen is completely released from the cell surface after treatment with phosphatidylinositol-specific phospholipase C.

Amino Acid Sequence↗
PubMed1989

Monoclonal antibodies against human leucocyte antigens. III. Antibodies against CD45R, CD6, CD44 and two newly described broadly expressed glycoproteins MEM-53 and MEM-102.

Monoclonal antibodies against several human leucocyte cell surface antigens were prepared and characterized: (1) MEM-56, MEM-93, MEM-66, and MEM-104 against the CD45R antigen (220 kDa and 205 kDa mol. wt. forms of the leucocyte common antigen CD45 expressed on B-lymphocytes, myeloid cells and a subpopulation of T-lymphocytes); (2) MEM-98 and MEM-100 against the T-lymphocyte antigen CD6 (mol. wt. 100 kDa); (3) MEM-85 against the broadly expressed antigen CD44 (mol. wt. 85 kDa) which was recently shown by us to be identical with the lymphocyte homing receptor; (4) MEM-53 against a newly described broadly expressed antigen of 35-40 kDa mol. wt. and (5) MEM-102 against another newly described glycoprotein of 40 kDa mol. wt. anchored in membrane through a phosphatidylinositol moiety.

Animals↗
PubMed1988

Monoclonal antibodies against human alpha-fetoprotein. Exploitation of an unusual calcium-dependent interaction with the antigen for analytical and preparative purposes.

Seven murine hybridomas were established producing IgG1 monoclonal antibodies (mAbs) against three different epitopes of human alpha-fetoprotein (alpha FP). The interaction of two of these mAbs (AFP-01 and AFP-02) with the antigen was strongly inhibited by calcium-chelating agents. The mAb AFP-11 could be used for estimation of alpha FP by RIA in the concentration range of 5-100 ng/ml. Several combinations of the mAbs could be used in a two-site sandwich-ELISA for similar purposes. Immunoaffinity chromatography on a column of immobilized mAb AFP-01 permitted the purification of alpha FP.

Animals↗
PubMed1988

Characterization of a 95 kDa human leucocyte sialoglycoprotein: its identity with CD43, gpL115, leukosialin and sialophorin.

A monoclonal antibody, MEM-59, was prepared, which recognizes a heavily sialylated glycoprotein antigen expressed on most human leucocytes, the apparent molecular mass of which is strongly dependent on the concentration of polyacrylamide gel used for SDS-PAGE. The antigen isolated on immobilized MEM-59 reacted in Western blotting with mAbs described previously by others as recognizing antigens of similar properties. These experiments indicate that the molecules called CD43, gpL115 (sialophorin) or leukosialin are identical and different from a 75-85-kDa glycoprotein of similarly broad tissue distribution (CDw44). Most of the anti-CD43 mAbs recognize sialic acid-dependent epitopes. None of the anti-CD43 mAbs tested stimulated proliferation of peripheral blood leucocytes in vitro.

Antibodies, Monoclonal↗
PubMed1988

Effects of silica pretreatment on allogeneic tumour growth in mice treated with lentil lectin, spleen extract or alloantisera.

The effect of silica treatment (5 mg intravenously) on tumour growth was studied with regard to three types of immunosuppression induced by: lentil lectin (LCA), spleen cell extract (SE) (active enhancement), and alloantiserum (AAS) (passive enhancement). Two experimental tumours were used, which differ in their sensitivity to humoral antibodies. CBA mice were challenged with Sa 1 (A) tumours and BALB/c mice with EL-4 (C57BL/6) lymphomas. The results indicate that silica treatment caused a time-dependent promotion of tumour growth. In passive enhancement, tumour growth promotion by silica treatment was obtained in both tumour systems. When silica was given along with LCA or SE, the two combined treatments had no enhancing effect on Sa 1 targets and enhancing effects on EL-4. The different behaviour of the two graft-recipient combinations is discussed in the light of the inherent properties of both experimental tumours and of the donor-recipient relationships.

Animals↗